The output of a two-inputs OR gate is fed to a NOT gate. Name the new gate obtained. Draw the logic circuit of the combination of gates. Give its logic symbol and write down its truth table.

Write the truth table of the following circuit. Name the gate represented by this circuit.

Write the truth table for the following combination of gates.

Identify which basic logic gates are represented by the circuits in dotted-line rectangles $1, 2$ and $3$ in the following complicated digital circuit. Give the truth table for the entire circuit.